Fuse member made of intimate mixture of powdered metals and method for making the same



3,167,628 E OF POWDERED THE SAME n- 6, 1965 H. M. LANG FUSE MEMBER MADE OF INTIMATE MIXTUR METALS AND METHOD FOR MAKING Filed Aug 4 1961 m QW mg; .g

INVENTOR. HAROLD M [Awe j cuuu 147' TORNEV United States Patent 3,167,628 FUSE MEMBER MADE OF INTIMATE MIXTURE 0F PGWDERED METALS AND METHOD FOR MAKING THE SAME Harold M. Lang, Syosset, N.Y., assignor to Sigmund Calm Corp., Mount Vernon, N.Y., a corporation of New York Filed Aug. 4, 1961, Ser. No. 129,417 8 Claims. (Cl. 200135) This invention relates to the art of fuzes and, more particularly, to an essentially or predominantly metallic fuze member that is adapted to be beneficially used as a thermal fuze, as an electrical fuze or as a combined structural and fuze element in a release mechanism assembly.

The word fuze (or fuse) has a wide variety of meanings. In addition to an electric current interrupting device it also refers to an initiating or triggering element. For example, it may act as a deflagrat-or to ignite an explosive, or may be used in connection with a mechanical release mechanism. It may also be used to transfer fire from point to point, sometimes at a predetermined and controlled rate, as, for example, in a time delay train. In this description and in the claims, the use of the word fuze is intended to cover, but is not limited to, all of the above applications.

There are two general categories of thermal fuzes, namely: (1) those which require an adequate supply of oxygen to initiate their destruction and which are hereinafter referred to as pyrotechnic fuzes, and (2) those which do not require oxygen to function properly. The latter category is exemplified by fuze members which are disclosed in James Cohn United State Patent No. 2,911; 504 and which are manufactured and marketed by Sigmund Cohn Corp, Mount Vernon, New York, under the trademark Pyrofuze.

Commercially available Pyrofuze fuzes, composed and formed as disclosed in said patent, comprise a first metal selected from the group consisting of palladium and platinum and a second metal selected from the group consisting of aluminum and magnesium. One form of Pyrofuze fuze is in the nature of a wire consisting of a tubular sheath, which is made of one of the selected metals, and a core within and in intimate contact with the sheath and made of the other selected metal. Another form of Pyrofuze fuze consists of relatively superposed layers of the selected first and second metals. Thus in both forms, the selected metals are present as concentric or relatively superposed layers which are essentially distinct from each other.

The teachings of said patent are considered an important advance in the art for the reason that the par ticular fuze members illustrated and described therein are known to perform their intended functions in an entirely satisfactory and dependable manner. On the other hand, those fuze members have certain inherent limitations. For one thing, they may not be machined or otherwise formed in certain regular or irregular shapes without altering the ratios of selected metal ingredients in portions thereof and, as a consequence, reducing their effectiv ness. Secondly, when they are made in sizes having relatively large cross sections, there is a possibility, in some instances, of the alumium ingredient melting out before the reaction proceeds properly, thereby adversely effecting the reliability of the fuze members in use. Thirdly, they are restricted in use to ductile metals and cannot be applied to metals of a brittle nature. F ourthly, their functioning time rate cannot be as precisely controlled as with pressed powder fuzes of this invention. Fifthly, they do not have the throwing power of pressed metal powders which are more active and which scatter hot particles with considerable violence in all directions.

A fuze member according to this invention successfully overcomes the stated limitations of Pyrofuze fuzes, while retaining all their desirable properties and characteristics.

The fuze member of this invention is related to the above-mentioned Pyrofuze fuzes to the extent that it may be made, at least in part, from palladium or platinum and aluminum or magnesium. The principal difference resides in the fact that, in the present invention, the fuze member is made from an intimate mixture of small grains or powders of the indicated metals instead of layers of such metals. The mixture is preferably pressed to desired density and formed by molding or machining to required size and configuration.

I have discovered that fuze members, whi h are made fro-m a pressed intimate mixture of powders of at least one metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold and at least one metal selected from the group consisting of aluminum and magnesium, possess a number of advantages over known related fuze members. Such advantages include:

(I) The functioning time of my fuze member, i.e. the time corresponding to the burning rate of pyrotechnic fuzes, may be faster or slower than that of ti e related fuzes, depending on its specific composition;

(2) My fuze member lends itself to being made in sizes of relatively large cross section and still operates in an effective and reliable manner;

(3) My fuze member may be readily formed by mold ing alone or by molding followed by machining into relatively complex shapes without modifying the ratio of its components and thereby impairing its utility or reliability;

(4) My member is adapted to be employed as a structural element in a release mechanism assembly, and when so employed, serves the dual functions of a mechanical device and a fuze; and

(5) My fuze member may also be employed as a fire transfer device, such as a time delay train, for the transferring of fire from point to point at a predetermined rate.

The primary object of this invention is to provide an improved fuze member which comprises an intimate mixture of selected powdered metals and which is adapted to be advantageously employed as an element of a thermal fuze or an electric fuze.

Another object of the invention is to provide a fuze member which is composed essentially of a pressed intimate mixture of selected powdered metals and which is capable of being readily made in desired sizes and in a wide variety of simple or complex shapes without adverse- 1y effecting its reliability.

Another object of the invention is to provide a fuze member wherein the ratio of the compressed ingredients is varied to conform to a predetermined programmed rate of burning, such as could be applied to a device for actuating or initiating operations of a planned sequential nature.

The invention has for another object the provision of an essentially metallic member which serves the dual functions of a structural element and a fuze element in an assembly of devices, such as a release mechanism.

Another object of the invention is to provide a pressed metallic powder fuze member whose functioning time rate depends largely on its specific composition and which is adapted for use as a time delay device.

A further object of the invention is to provide granules of pressed powders, each granule having the preferred composition and possessing all the desired characteristics of the massive form. Such granules, for example, may be used as a modifier in connection with the burning of solid propellants, controlling the burning rate.

It is a still further object of the invention to provide a enemas fuze member of the character indicated that is reasonable in manufacturing cost and that is capable of performing its intended functions in an entirely satisfactory and reliable manner.

The basic composition of a fuze member of this invention comprises an intimate mixture of from 95 to parts by weight of a powdered first material consisting of at least one metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold and from 5 to 80 parts by weight of a second powdered mtaerial consisting of at least one metal selected from the group consisting of aluminum and magnesium. This composition may consist essentially of the indicated powdered metals or may also include an active or inactive supplementary material, depending on the desired functioning time and the intended use of the fuze member.

The ingredients of the fuze member may be in a relatively loose state, requiring support, or may be pressed or compacted to obtain a member having requisite physical properties.

Although the product will function as a mixture of powders, if it is decided to use it in a finely divided state it is advisable first to compact briquettes or pellets and then subsequently crush these to the desired grain size. In this way, each particle is an intimate mixture of the ingredients and better performance may be expected from them than from a loose mixture of the individual powders.

The fuze member of this invention has wide application. It may be used, for example, as an element of an electrical fuze or a thermal fuze, as a structural element of a release mechanism, as a time delay train or as a modifier for solid propellants. The specific composition, the functioning time rate, the degree of compaction, the size and the configuration of the fuze member are determined by its intended use.

The term powdered, as used in this description and in the claims, has reference to small or fine particles, without regard to their configuration, and includes grains, granules, flakes and the like of the various components.

The expression supplementary material, appearing in this description and in the claims, refers to at least one organic or inorganic additive which does not participate directly in the thermal reaction of the indicated powdered metals, but which acts as a structural reinforcement, inhibitor or modifier. Various supplementary materials of a physical shape which is compatible with a specific application may be employed and include talc, graphite, ground glass, infusorial earth and the like, and may include reenforcing fibers of various materials. The supplementary material may also comprise one or more metallic fillers, such as nickel, which do not react with the active powdered metal ingredients. Moreover, the supplementary material may consist of or include a liduid vehicle in which the active powdered metals 11% dispersed. Such liquid vehicles may include, for example, various paints and similar compositions which are adapted to be readily spread and form films or coatings of desired length, width and thickness and containing the active metals.

The compositions of several preferred and recommended pressed powder fuze members according to this invention are identified below:

Example No. 1

A fuze member consisting essentially of 75 parts by we1ght of palladium and parts by weight of aluminum.

Example N0. 2

A fuze member according to Example No. 1 and containing graphite in an amount equal to about 0.5% of the total weight of the palladium and the aluminum components.

4. Example N0. 3

A fuze member consisting essentially of parts by weight of palladium and 20 parts by weight of aluminum.

Example N0. 4

A fuze member according to Example No. 3 and containing talc in an amount equal to from 1% to 15% of the total weight of the palladium and aluminum compo nents.

It was ascertained that the functioning time rates of the foregoing examples vary with the particle size and form of the palladium and aluminum components and the particle size and amount of the added supplementary material component. I found that fuze members of Example No. 2 in which both the palladium and the aluminum were granular and had a 325 mesh size, i.e. capable of passing through a standard measuring screen having 325 openings per linear inch, have a functioning time rate of approximately 40 milliseconds per inch. Other fuze members of Example No. 2, but employing about 1000 mesh flake aluminum, were found to have a functioning time rate of approximately 270 milliseconds per inch.

Puze members of Example No. 3, in which both the palladium and the aluminum were granular and 325 mesh, were found to have a functioning time rate of approximately 39 milliseconds per inch.

The relationship of the amounts of talc used to the functioning time rates of several fuze members of Example No. 4 is indicated in the following table:

Functioning time rate in milliseconds per Amount of talc: inch (approx.)

The small amount of graphite, namely 0.5%, was incorporated in the composition of Example No. 2 for the primary purpose of serving as a mold release so as to facilitate removing the pressed fuse member from its mold. It is believed that the graphite also acts as an internal lubricant permitting the particles of the selected metals to move more freely during the step of compacting the composition.

The drawing illustrates an assembly of one of many forms of devices according to this invention and adapted to be advantageously used as a release mechanism. In the drawing:

FIG. 1 is a view in central vertical cross section of the assembly of devices;

FIG. 2 is a top plan view of FIG. 1; and

FIG. 3 is a view taken along line 3--3 of FIG. 1.

Referring to the drawing, the assembly comprises a support 5 which, as shown, is positioned horizontally and is provided with a vertical through opening 6. A loadcarrying member 7 extends through opening 6. Member 7 is preferably in the form of a metal rod having a threaded upper end portion 8 and a threaded lower end portion 9. A nut 16 engages threaded end portion 9 and bears against the bottom surface of support 5 to restrain member '7 against upward movement relative to the support. A load (not shown) is adapted to be joined to and suspended from member '7 by a suitable connector means (also not shown) which engages the threaded lower end portion 9 of that member.

A tubular retainer 11 is disposed above and bears against the top surface of support 5. The lower end of the retainer has an opening 12 which is aligned with and slightly larger than opening 6. The upper end of the retainer is internally threaded, as indicated at 13. The retainer is provided with a plurality of integral internal ribs 14 which extend in a longitudinal direction and are spaced from each other.

Positioned wholly within retainer 11 is a coupling member 15. Member is preferably in the form of a nut which engages the threaded upper end portion of member 7 and which is provided with a plurality of spaced longitudinal grooves 16. Retainer ribs 14 register with corresponding grooves 16 and prevent relative rotational movement between the retainer and the coupling member. Coupling member 15 is made from a pressed powder composition of this invention.

There is provided a tubular member 17 which serves the combined functions of a squib holder and a jamb nut. This member is tapped, as indicated at 18, and is externally threaded, as indicated at 19, for engagement with retainer threads 13.

A squib unit 20 for creating suflicient heat to efi'ect thermal reaction of the active metal components of member 15 is carried by member 17. The squib unit includes a receptacle 21, which is formed with external threads that engage the threads 18, a nut type turning head 22 and a pair of electric leads 23 which are adapted to be connected to a suitable source of electric energy supply (not shown) for operating the squib.

For the purpose of outlining the operation of the illus trated embodiment of the invention, it is assumed that the parts are assembled and in the relative position shown in FIG. 1, that electric leads 23 are connected to a suitable source of electric current and that a load is connected to load-carrying member 7 and exerts a downward force on that member and associated parts. When squib 20 is operated, it creates suflicient heat to raise the temperature of the aluminum and/or magnesium components of member 15 to their melting points. This causes a very rapid exothermic alloying reaction of the active metal components of member 15 with the evolution of a considerable quantity of heat. During this reaction, member 15 becomes molten and member 7 is released therefrom and moves downwardly through openings 12 and 6 due to the force exerted by the load.

A number of release mechanism assemblies of the character shown in the drawing have been made, tested and found to operate in a satisfactory and reliable manner. Among such assemblies were several which employed the composition of Example No. 2 for coupling member 15 and a threaded /4 inch rod for load-carrying member 7. These assemblies were capable of normally supporting a load of 5,000 pounds. The total functioning time of each of these assemblies was approximately 95 milliseconds, including about 20 milliseconds for the functioning time of the squib unit.

The illustrated release mechanism assembly is adapted to support a suspended load and contemplates making coupling member 15 from a pressed powder composition of this invention and load-carrying member 7 from a conventional metal. It will be appreciated that the parts of the assembly may be readily rearranged with minor changes so that the load-carrying member will normally be stressed in compression instead of tension. Also, the load-carrying member may be made from a composition of this invention while coupling member 15 may be made from a conventional metal. Moreover, it should be borne in mind that various other known forms of interconnected load-carrying members and coupling members may be substituted for those shown in the drawing. For example, member 15 may be in the form of a key which registers with openings that are provided in member 7 and retainer 11.

As was mentioned earlier herein, the present fuze member may be used as a time delay element. Such an element may be employed to transfer fire from one location to another at a predetermined rate of time. The element may be in the form of a pressed rod. Its functioning time rate may be readily controlled by varying the particle size of the selected active metals, the particle size and amount of the supplementary material (if any) and the degree of compression, i.e. the density, of the rod.

The fuze member of this invention may be formed in small pellets of requisite size. It may be further crushed or granulated to provide a finely divided consistency, retaining its original functioning characteristics and be usefully employed, for an example, as a combustion modifier when mixed with solid or liquid fuel.

This invention also contemplates forming a fuze member from a composition comprising a mixture containing an appropriate liquid vehicle, such as paint, and powdered selected active metals described above. The composition is spread on a base, by brushing or in any other suitable manner known to the art, and allowed to dry and form a film or coating. Additional films may be successively applied to the first film to obtain a final fuze strip of desired length, width and thickness.

An alternate method is to simultaneously flame spray the individual metals in correct proportions onto a surface that may be of any desired shape. A deposit is thus built up of the component metals in intimate contact with each other, and may be removed from the surface or left on it, as desired.

From the foregoing it is believed that the objects and advantages of the herein described fuze member and the embodiment of the invention illustrated in the drawing will be apparent to persons trained in the art, without further description. It is to be understood, however, that the invention may be embodied otherwise than as here described and illustrated, and that various changes may be made without departing from the spirit or sacrificing any of the advantages of the invention.

I claim:

1. A fuze member comprising an intimate mixture of at least one powdered metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold and at least one powdered metal selected from the group consisting of aluminum and magnesium.

2. A fuze member comprising a pressed intimate mixture of at least one powdered metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold and at least one powdered metal selected from the group consisting of aluminum and magnesium.

3. A fuze member consisting essentially of an intimate mixture of from 95 to 20 parts by weight of a powdered first material consisting of at least one metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold and from 5 to parts by weight of a powdered second material consisting of at least one metal selected from the group consisting of aluminum and magnesium.

4. A fuze member consisting essentially of an intimate mixture of from to 20 parts by weight of a powdered first material consisting of at least one metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold and from 5 to 80 parts by weight of a powdered second material consisting of at least one metal selected from the group consisting of aluminum and magnesium, and a supplementary material.

5. An assembly comprising a support, a load-carrying member, and a coupling member connected to the loadcarrying member and to the support for normally preventing movement of the load-carrying member relative to the support in at least one direction, one of the members comprising a pressed intimate mixture consisting essentially of from 95 to 20 parts by weight of at least one powdered metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold and from 5 to 80 parts by weight of at least one powdered metal selected from the group consisting of aluminum and magnesium.

6. A composition for use in forming a fuze member comprising a mixture consisting essentially of a liquid vehicle, at least one powdered metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold and at least one powdered metal selected from the group consisting of aluminum and magnesium.

7. The method of forming a fuze member comprising the step of simultaneously flame spraying onto a selected surface streams of a first material and a second material, which streams converge and intersect proximate said surface, said first material comprising at least one metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold, said second material comprising at least one metal selected from the group consisting of aluminum and magnesium.

8. The method of forming a fuze member comprising the steps of simultaneously flame spraying onto a selected surface streams of a first material and a second material, which streams converge and intersect proximate said surface, said first material comprising at least one metal selected from the group consisting of palladium, platinum, rhodium, ruthenium, iridium and gold, said second'material comprising at least one metal selected from the group consisting of aluminum and magnesium, and separating the product formed by the preceding step from said surface.

References ited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Pyrofuse, Exothermic Fuse Wire; Pyrofuse Corp., copyright 1960; pages 1-3 relied upon. 

1. A FUZE MEMBER COMPRISING AN INTIMATE MIXTURE OF AT LEAST ONE POWDERED METAL SELECTED FROM THE GROUP CONSISTING OF PALLADIUM, PLATINUM, RHODIUM, RUTHENIUM, IRIDIUM AND GOLD AND AT LEAST ONE POWDERED METAL SELECTED FROM THE GROUP CONSISTING OF ALUMINUM AND MAGNESIUM. 